Food Allergies

A food allergy is when the immune system mistakenly responds to a food protein, resulting in inflammation or damage to the intestinal tract. Allergies can present with an immediate or a delayed reaction.

What Is a Food Allergy?

The immune system helps to protect us from infection by identifying and attacking bacteria or viruses that can cause illness.  When the immune system mistakenly responds to a food protein, inflammation and damage to the intestinal tract may result.  However, having a food allergy does not mean that your child is at increased risk of infections.  

How Common Are Food Allergies?

About 5% of all children under the age of three years are allergic to one or more foods. They most often react to milk, eggs, soy, wheat, fish, peanuts, and berries. However, almost any food protein can cause an allergic response.

Why Do Food Allergies Happen?

The reasons why food allergies occur are not clearly understood, but a child is more likely to develop food allergies when other family members have asthma, eczema, hay fever or allergies.

What Are the Types of Food Allergies?

Food allergy can present with an immediate or a delayed reaction.  In immediate reactions which occur within minutes to hours, the child may develop hives, wheezing, or swelling of the face as well as tightness of the chest. The reaction can be so severe that the child cannot breathe (anaphylaxis). Emergency treatment is needed. Luckily, these dangerous reactions are relatively uncommon. 

Delayed reactions occur from hours to days after eating the offending food.  Symptoms may include vomiting, pain, diarrhea, blood stools, or poor growth. Some children may have hives or eczema.  Delayed reactions are the most common form of food allergy.

What Are the Symptoms of a Food Allergy?

Symptoms of a food allergy can include:

When food allergies cause gastrointestinal problems, they may be evaluated by a gastroenterologist. At other times, the child may be seen and evaluated by an allergist or immunologist. Frequently these specialists work together. (Copy adapted with permission from NASPGHAN, the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition.)

How Is a Food Allergy Diagnosed?

Skin prick tests and RAST (blood) tests are used to test for foods that might cause an allergic reaction. A negative test for a food tends to rule it out. A positive test means that the food might be involved, but it does not mean that the child will definitely have an allergic response to that food. 

Your doctor may do an endoscopy to take biopsies (tiny samples) of the lining of the intestine to look for inflammation caused by allergies or an immune system reaction.

limited elimination (or hypoallergenic) diet may be tried to see if symptoms go away when common allergy-causing foods are not eaten. If the child is better on the elimination diet, foods are gradually added back to see if symptoms return.

How Is a Food Allergy Treated?

The treatment of food allergies includes the avoidance of the offending food. Children with a history of severe allergic reactions should care an Epi-pen® at all times.

What Can I Expect If My Child Has a Food Allergy?

The majority of children allergic to milk, soy, eggs, and wheat will “outgrow” their allergy by the time they are five years old, if not sooner. Those who are allergic to nuts, seafood, and some other foods may have to avoid these foods for life. It is important to talk to your child’s doctor before reintroducing a food that your child has been allergic to in the past.